The album sees Farid Bang rapping about his gym regime, boasting that “my body is more ripped than an Auschwitz prisoner’s.”

Kollegah, meanwhile, was targeted with claims he was anti-Semitic after a 2016 music video which appears to show a Jewish man at the head of a secretive global banking conspiracy.

Open letter to promotors

Now the controversy has spread to Switzerland with an open brief signed by an alliance of local politicians, queer groups, and women’s rights organisations calling for their appearance at the upcoming Albanian Festival in the city of Schaffhausen to be called off.

Addressing the concert’s promoters, the letter’s signees argue the rappers “glamorize violence” and “damage the dignity” of groups including refugees, homosexuals and women.

Among the supporters of the move is local Socialist Party politician and rapper Patrick Portmann, who says he has received verbal threats because of his stance.

“Obviously they have interpreted our protest against the rappers’ text as [a protest] against the fans too,” said the politician and rapper who now wants to retreat from the front line of the confrontation, according to Swiss daily Tages Anzeiger.

As a rapper himself – he goes by the name of Sympaddyc – Portmann believes fans think he has betrayed their idols. He says the fans believe that what their fans to is art, and that means anything goes.

The German rappers themselves have denied claims they are anti-Semitic.

On Monday, the operators of the BBC Arena concert venue addressed in the letter said responsibility for the concert lay with the Alba-Kulturverein cultural organisation and that they saw no indications the event could contravene local laws.